Armor plate and process of making same



Patented i i.

Y ARMDRNPLTE Amore-boese os-MAK'NGsAME.

""To all whom itfmyxc'ofrwem: l l

.iBe fit1 knownirthati I, leHNi Lx Cox f 5 yof *.Ptennsylmnia, have -.-.r-inxtented :ea'ifnew soripton.

byzr'carburizing; thefacelrof al forged 'plate 35 Y tol ai depth varying with lthe itlhi'c'kness: "of fthe plirte51. usually 'aboutv v eight@ :tot .ten Aper centi.l ozsnch thickness; ithen ireforging, rthen heet.I ing to :tf-.hightemperature vto permit -suehi:

rearmngfen'ient ofv the' ymele cules- 'asiwill i produce,1 upon:sudclenvl eo'olingfsa line-'grained ffmoleeular structure, suddenly eo'oling'fthe plate; their Teh-eating Sthe': platef to ai lower to produce hardening, and thren'lsuddenly carburized :face thereof l Partf of thisV proeess lis". disclosed 'fintlieEhrensbergerY10-atente :j

i of. eight? inc-bes' L; or filess iinthiclmess el- 2 ktheughi fits applicationnto leinem :the thickest armor produces; aiplatewhieh: i is distinctly superior to ai' plategpreclucecl; bycany. of .fthe

l Invpr-i'ori processesl ofi theeharaeter decarbon feont'e'nt and fits possible rate-ofcooling permit. vAllfithe metalsoheatedaboveits hardening pointandv quenched. Will Ishow speotiveofythe thickness Aoffthe y'la-yer of'baek Y metalthushafrde-ned,afurtherzoneof VeensidLeiablevlthiekness@will halve been 4heat-'ed to j ened-'andim-aeleeasytf penetration; f

af citi?k zenvof rtheUnitetl Statesgi'residi ng fa Rh Ailedelphia,tcounty-lof::RhiladelphiafanalStateii In the lnanuiacture of: armoe platei-tiiis a known desicleratum toi provide c the same Y with-a hardiacefancl; a ,teugh back. This hasl heretoforebeen.aeeomplislrelffor example! "I available-y eteisile n strength` :andi elastic limit combinedwithA absence of? a crystalline :fo-1` f `supe1"oarlmriztcl'v zene,' andf a 'j layerf ol fthe'- general metal f theplatea-lsoheatecl abovei its"- hard'eningfpoint i and fthenf; hardened byy the face-quenchingl'to y"the-extent that its? Blateeefthie @hamer-er1mayrfteeak up the? l carbon, ofl'course i j jeppiibatioeledf :January-s, S1921, .seifiai No. 435;'535.

` faces Onfthe eontrary,rthe projectile cracks and spalls away the surface of the plate and penetrates the unprotected asoftmetal of Vthe back, :rebounding entire fior fcompletely iper--` "f .forating the, plate,A clepentlingrupon the finifl fandnusefulfImprovementsinlArrmorPlateij andA Brocesses mf:-;Mal{inga"Sanie,'= of; which if; the` followinggis a ifull',,ielearfianclxexact def.

- v"hard-er than'ithebody orrback and.presents'y .The object ofmy invention i is Lto y.fproviclci to the attack -of a .projectile metal highly@ plateis composed of'inetal `With the highest mationftvhichffaeilitates cnaeking and. pe'ne-l i sistaneeto afprojieetile'whieh m'aygliave perforated the'fae'ezone, and absorbs at .an un-'V er projectile'. A

i`-.tration. Such a backjepposescontinuedre''f su'p'erleial. penetration. than the pl-ates.; gen` erally fin use, fbut:unoref:resistancey itof. com-r plete i per-foretion,'whieh is of muelle great-f erfiimportanee;'-whilepgduetothe absence ofi cracking or ,spallin'ggthej:resist/ence. tto; pene- A Y tration atzfanypointtfisi fnotfidestroyedn and: but little: ,climishedty by ai preuieus: .exposure coolingmeither.1the-f`Whole plate'for'onlythe 'fi'ireLatiainacljaeent:point t c The invention; 'sepeticeiany eppiicatie 'to g relatively fthin armor; 'plate-say; plates;

pnoeess'esj heretofore' in `generali use. f L

I' y prefer; that the; plates t be` treated shall have a relatively 1 high'. carbon centena-esa E'fromDaB/l tofLOgtlpeiicentcarboni` i Y Y,inzeeuburizing:thefplatefit isfdis'tinetiyely i A preferable, although @not intlispensable', :to 'earburize mure g' deeply fzthan heretofore Thus, in thelcase of twelteinch 'or thirteeninch plate",v I prefer tol carburiae to `:the depth of "I from lone and 'one-helffrto two inches, Whilein theeaseot anfeight infch plate I prefer to :ea'rburiz'e tolaY depth ofxront one inch tooneand onehal inches; zin othertyordsyito* av depth notless than about twelve'perfcent f "Of ille 'thkllessiofl-the Plate; c l f f 5I .prefer @thatithenearbo-nif' contenenti-1 the After the-V customary precautionary `Ineasui'es directed to prevent the cracking of the plate when cooled from the high temper?,k

ature or" carburization, the plate is cleaned and the face protected from oxidation byv suitable carbonaceouscovering Y Y. The plate is then reheated to a very low forging heat, say Vabout 1900@ F5., and 'forged down to final thickness, care being taken toVA Work the carburized face metal asthorou'ghly as possible. f

iardeningpreferably to torni 14150 F. to 225 F. above that temperature'. in the `case or' nickel-chrome steel of a known composition,

. lhaving an average critical or A01 point of V`about 1380o F., the preferredtemperatureA of heating Wouldbe in the neighborhood ot'- 1600F. l 'Y The plate is thenv cooled'fsuddenly', kpreferably quenched -by spraying.. rllhe resultV is! a ine-grainedmolecular structure.

TheV Whole "platemis then uniformly re- `heated to rsoinevvhat Aabove ,the aforesaid.

f criticalteniperature, say tofabout 100o F.'

' of 1380o F., 4the preferred temperature` Would be about 1&7 5 F.- Less preferably,

above that temperature. V-Infthe case of alloy steel, having the samef'critical point the 'platemay be heated to a high temperature, or even toa temperature approaching Yplate,,heating the Whole ,plat-ete a low forging temperature and reorging, heating thea or-'equal to thatgoftheftlrst heating, but in such cases, care niust,v be exercised to limit.V

the heating to a considerably -shorter time. It -isV found'distinctly advantageous to keep the plate at a temperaturefsomewhat above the temperature of the kcritical Apoint for a relatively long timefrather thanA to keep itr substantially abovek thecriticaly .point for a shorter'time. The plate is again cooled suddenly, preferably quenched by spraying, as

. stillturther refines the grain..

The Whole plate is then again uniformly in the first heat treatment. "This operation `reheate'd to a temperature'preferably not in plater issuddenly quenched, as by spraying.y

excessy of Y1225" F.. and bentto'A shape or straightened.VV Any temperature used for i `bending which is in excess of that required l tic limit ot' the material. f -J by the next step is at a sacri-tice of the'elas- After bending, fthe? plate is uniformly re-V l heated to a temperature above 1100? `but so farbel'ow the critical point that after quenching .no hardening Will result. the

.Undeicertain conditional haveto'und it possiblete give tlielinalr'iluenchA from as low as 1050o s i If the preceding steps have been properly carried out, the plate, on fracturatvill not "i havea granular appearance, but will haver 'A 1f ialiiloroi'is appearance, both in--the uncarbu-V ,rizedbody and through allv or ine-arly all of kthe carburized face. YIn other Words,.the

{ibrous appearance, instead of, as inplates treatedby conventional methods, being conlined toa zone at the back, leaving the entire carburized VAzonegand a deep intermediate zone withfa granular'appearance, extends almost to lhe'sur'iace o the carburized tace.

Theteinperature of this last Aheating should not exceed a Ltemperature approximately 100o below the critical A01 point of the steel K at that stage of manufacture., v

As the `structureof the steel has'become finerduring the heat treatments described, the critical A01v temperature has fallen, and, Vfory the steelchosen, at thevlast stage ,is

probably Vnot in lexcess of 13250 F. lThe 'qu-.ence is, preferably,atsnot'overV 172259 F., Ynorflessfthan 10500 FJ-tlie lower the bet-v ter vprovided full tibrosity, so-called, is obtained. A temperature of aboutllSO". F.

` is "usually satisfactory; i

` Itis inipossible'to give'moreexaot ranges of temperatures than those specified, because the preferred, as Well astliernaxiinuin and y`Inirnimuinltemperatures, -will vary with the l, critical temperature of the metal, Which in Whole plate rto above 'the critical tempera ture orp the metal` then suddenly cooling,

heating the Whole: plate to at leastitheeriti-y .cal temperature, but not to the extent of the lii'st heating, lthen suddenly *cooling heating the Whole plate (which has thus been ygrain-refined) to a temperature so far below the critical temperature that, upon subsequent sudden cooling, theplatavfon fracture, will presen-t substantially throughout ra fibrous appearance without substantial crystalline kmaterial, andy then` suddenlyv cooling;

2. Tl`he-vprocess off making arinorsplate.

which comprises .caiburizing one face of the plate, heating` the Wholeplate to a lowl torg- Aing teniperatureand lre,-rorgin'g, heating the Whole platetov above the critical temperature ofthe nietahtlienSuddenly cooling, heating' the Wholeplate to jaboye `the critical tern-Vv Y perature but to 'atempeiature .lower than Vdesire `to protect.- by Letsov iiov

lao

that ofthe rst heating and n otk more than degrees E. above the critical', temperature, then suddenly cooling, heating the Whole plateto alteinperature so :far belowA the critical temperature that, upon subsequent suddeii cooling, the plate, ontracture,

will presenti, substantially throughoutv a,

Vtibrous appearance yand AVthensuddenly cooling. i

BQThe process of making armor Lamela f which :comprises carlzuiri,,zing one ,.ffa'e'e., ofithe rplate,heating@thefwhole platetoga ilowr., forging, temperaturefandLreforging, hea-ting Y l the whole platetd a'temperature above,- but not;`r moreft'han.250 ldegrees kF. above,.the j critical temperature, then suddenlyeooling,

heating the Whole plate to at least the critical temperaturegbnt-iiot to the extent vof the first heating, then suddenly cooling, heatingy the vwhole plate to a temperatureso far.below the critical temperature that, Aupon subsequent sudden cooling, the late, onfracture, will V'present substantia y throughout a fibrous appearance, and then suddenly cooling. l Y

4. The process of making armorA plate which comprises .carburizing one face'r ofthe plate, heating the whole plate to a low forging temperature and ire-forging, heating the whole plate to atemperature above the critical temperature of the metal, then suddenly cooling, heating the whole Vplat-e to atleast thecritical temperaturebut to a temperature lower-than that of the first heating and not v degrees F. above the critical temperature,

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' more than 75 degrees above the critical tem-k perature, then suddenly cooling, heating the whole plate to a temperatureso far belowv Athe critical temperature that, upon subsequent sudden cooling, the plate, on fracture, will present substantially throughout ka .fibrous appearance, and then suddenly cooling.

5. The process o-f making armor plate which comprises carburizing one face of the plate, heating the whole plate to a low forging temperature and re-forging, heating the whole plate to above the critical tempera*y ture of theV metal, then suddenly cooling,

heating the whole plate to at least the criti cal temperature, but not to the extent of the temperature, then suddenly cooling, heating the whole plate to at least the critical"tem. perature but to a temperature lowerthan that of the first heating and not more lthan then suddenly cooling, heating the whole plate to a temperature not higher than'k 100 f degrees F. below the criticalv temperature but sufficiently high to secure fibrosity, and

then suddenly cooling.

7. rIhe Vprocess of making armor plate,

which comprises carburizing one face *of the plate, purposely left somewhat thiclrer than its:v dimension afterWiardiv .he ating .ythesA y n whole plate-to;` a very low. forgingheati andL completing the `=`forging ato,- thickness iheating the whole plate to considerably, above vthe crit-ical.;temperature. of .the metal, "tl-ien sudden'ly -coolingfheating thefrwholel platetol somewliat.I :abo re .l 'the g criticaly temperature,

bntnotfto the extent oftheir-tsheating,ftlien f lsuddenly cooling, heating the-whole plate Whichhas been thus grain-reiined to V a tem' peratuie of about 125C F., below the critical temperature of the metahthen cooling'the f plate, heating 'the whole plate to a temperal.ture so far below the critical .temperature that upon sudden cooling, the plate, on frac- -,ture. will present substantially.throughout a fibrous appearance without lsubstantial crystalline material, and then suddenly cool- 8. The

which comprises carburizing one face ofthe Mplate, afterward heating the whole plate to a processsof ymakingarmor plate lverylow forging temperature and re-forging A the plate, rcheating the whole plate to labove the critical .temperatureL of the metal, then suddenly cooling, heating the whole plate'tov above thecritical temperature but to a temperaturelower than that of the second heat-v ing and notfmore than 1250'F. above the critical temperature of the metal, then suddenlycooling; reheatingthe whole plate to atemperature of about 125 F .below the critical temperature of the metal, cooling the plate, reheating the whole plate to a temperature so` fary below the critical temperature that upon subsequent sudden cooling,

the plate, onfracture, will present substan` tially throughout a fibrous appearance,`and then suddenly cooling. Y

9. A heat-treated armorplate of alloyed steel, `which is highly carburized yfrom one face inward,which is substantially devoid of crystalline Vmaterlial, and presents, .on I

fracture, a fibrous lappearance throughout the uncarburized back, as wellas the majorl portion of the carburized face.`v

l0. A-heattreated non-'facekhardened armor platevof alloyed steel, highly carburized on one face, and of essentially uniform physical properties'throughout the unearburized portion.A

plates thickness, and of substantially uniform physical rproperties' throughout the uncarburi'zed, portion. f

. 12. Aheat-'treatedy armor plate of alloyed` steel, highlyV carburized freni one face inward toa depth equal to ayrelatively ksmall part of the thickness of theV plate, substantially devoid of crystalline material and pre- ,l1. heat-treated armor plate' of alloyedl steel, carburized from one face inward to a. depth. in' excess of eight percent of the ilsV ".sentingj onffracture, a4 fibrous Vappearance throughouty the 'unca'rburized portion, and

the Whole ofthe 'uncarbur- 13. Allem-treated armor plate of elloyed steel,v having a body Whose whole minimum cei'bon content is not less than 0.32 percent and Which'is carburized from the 'face in- Y werd tifa depth 'of' at leastV twelve per cent of the thickness of the plate,vthe carbon con- 1n tent of theface not exceeding 14 per cent. lin testinony'of Which invention, I have hereunto seit my hand, at Philadelphia Pa.`,`

on thisBOth day'of December, 1920.

' JOHN VL.- oox. 

